PSFTP connection failed
What “PSFTP connection failed” usually means
When PuTTY reports PSFTP connection failed, the client has already attempted a network or protocol step and failed before a normal interactive shell is available. This guide explains what the message usually means on Windows clients, which local settings to verify first, and when the problem is almost certainly on the server, firewall, or DNS path rather than inside the PuTTY GUI.
PSFTP could not establish an SFTP session—underlying SSH connection failed or the server disabled the SFTP subsystem.
Independent resource: Putty.info is educational only and is not affiliated with the official PuTTY project. Compare symptoms against the official documentation for your installed version.
Symptoms you will see
Operators usually notice this failure in one of a few repeatable ways. Capture the exact dialog text, the hostname and port from the Session panel, and whether the failure happens before or after a username prompt—those details decide which checklist below applies.
- PSFTP exits before an sftp> prompt.
- GUI SSH may still work if only SFTP subsystem is broken.
Likely causes ranked by frequency
Several independent conditions can produce the same client-facing wording. Work from the outside in: reachability first, protocol selection second, authentication third. Changing key files will not fix a TCP refusal, and opening a wider firewall will not fix a rejected public key.
- Same TCP/auth failures as PuTTY.
- sshd Subsystem sftp line missing or broken.
- Chroot/SFTP-only setups rejecting the account mode you used.
Step-by-step client checks
Use this ordered checklist on a workstation you control. Prefer saved sessions so Host Name, Port, and Connection type stay consistent while you isolate one variable at a time.
- Prove interactive SSH first with the same credentials.
- Retry PSFTP with explicit user@host and port flags as documented in the PSFTP guide.
- Confirm Pageant keys / PPK arguments mirror the working GUI session.
- Ask admins whether SFTP subsystem is enabled.
- Test with a simple ls once connected before complex puts.
- Distinguish auth failure messages from subsystem failures.
Do not paste private keys, passphrases, or production passwords into Putty.info tools or contact forms. Diagnose locally with PuTTY, Plink, PSCP, or PSFTP from an official install.
When it is a server or network issue
Verify Subsystem sftp internal-sftp or path to sftp-server. Match rules may allow shell but not SFTP—or the reverse.
If TCP connects from another network path but fails from yours, involve the network team with traceroute/path evidence rather than repeatedly regenerating keys. If authentication fails after a banner appears, collect the server sshd logs for the same timestamp and username—client-side retries alone rarely reveal AccountLocked, Match blocks, or AllowUsers denials.